This invention relates generally to improvements in manufacturing processes and methods used to produce plastic encased tool components and the like. More particularly, this invention relates to an improved method of making plastic molded tool components having a lightweight hollow core, wherein the hollow core is structurally reinforced during molding processes to prevent damage thereto.
A variety of plastic encased tool components are generally known in the art, wherein a skeletal core member is contained within a resilient outer encasement or cladding of molded plastic material or the like. The tool component is produced by placing the skeletal core member into a mold cavity which is then filled with a selected thermoplastic molding compound under suitable conditions of heat and pressure. The plastic material is permitted to cure, followed by removal of the plastic encased tool component from the mold cavity. Examples of such plastic encased tool components include elongated tool handles, plastic-faced hammers and mallets, etc.
In the production of tool components of this general type, the skeletal core member must have sufficient structural integrity to withstand the pressures and temperatures encountered in a typical injection molding environment. That is, the core member must be able to retain its structural size and shape throughout the injection molding process, to prevent production of defective tool components. In the past, skeletal core members of solid cross-section have been commonly used in the manufacture of plastic encased tool components. However, since the cost of such tool components is primarily attributable to the cost of materials, it is desirable to reduce or minimize the material used in the skeletal core member to the extent possible without sacrificing the requisite strength and stiffness. In this regard, mere reduction in the cross-sectional size of a solid core member is ineffective to reduce materials cost, since additional molded plastic encasement material is required to form the finished tool component.
Hollow skeletal core structures have been proposed for use in the manufacture of plastic encased tool components. A hollow core member beneficially reduces the material cost in the finished tool component, without requiring the use of additional molded plastic encasement material. Moreover, a hollow skeletal core reduces the weight of the finished tool component, resulting in a lightweight tool product which can be especially desirable in certain applications. However, despite the hollow construction of the skeletal core member, a substantial amount of core member material has still been required in order to provide the core member with the necessary structural integrity to withstand injection molding processes.
There exists, therefore, a need for further improvements in manufacturing processes for making plastic encased tool components, wherein a hollow core member constructed from substantially minimum material quantities is contained within a resilient outer encasement of molded thermoplastic material or the like. The present invention fulfills this need and provides further related advantages.